600hp high boost, when do i o-ring the block???
The gasket doesn't 'care' what size turbo or how much boost is used. All the gasket cares about is pressure - either the mechanical pressure of torque, or detonation. In this case, the OP is almost certainly not generating enough torque to stress that gasket. If there are no obvious signs of detonation present(?), then the gasket itself can be ruled out as the cause. And where detonation is present, an effective MLS gasket arrangement will often cause a piston ring land to break first. Additionally, if there is a high heat situation in the top of the block, that can create surface distortion that results in sealing issues. This is mostly a concern for high specific output applications (e.g. >1000whp).
To effect a proper seal, that gasket requires the appropriate straightness and fine finish on deck and head surfaces, and even loading across the fasteners. As sure as death and taxes, there are many instances where surfaces were improperly prepared for a MLS gasket (e.g. >RA 30), and there are many more where the studs and nuts were improperly installed and/or torqued.
Competent o-ringing involves a stainless wire where a receiver groove is machined into the mating surface, or a more malleable copper wire where no receiver groove is used. The diameter of that wire and depth of its groove must take compressed gasket thickness into consideration and be sized accordingly, or it will simply be ineffective. But o-ringing isn't needed here.
More often than not, the problem is with the installation/torquing of the studs and nuts, and 'more' doesn't equal 'better'. If one installs the studs finger snug, uses the latest ARP lube, and doesn't overtighten the nuts, they need no retorquing, and are very reliable in a 4G63.
To effect a proper seal, that gasket requires the appropriate straightness and fine finish on deck and head surfaces, and even loading across the fasteners. As sure as death and taxes, there are many instances where surfaces were improperly prepared for a MLS gasket (e.g. >RA 30), and there are many more where the studs and nuts were improperly installed and/or torqued.
Competent o-ringing involves a stainless wire where a receiver groove is machined into the mating surface, or a more malleable copper wire where no receiver groove is used. The diameter of that wire and depth of its groove must take compressed gasket thickness into consideration and be sized accordingly, or it will simply be ineffective. But o-ringing isn't needed here.
More often than not, the problem is with the installation/torquing of the studs and nuts, and 'more' doesn't equal 'better'. If one installs the studs finger snug, uses the latest ARP lube, and doesn't overtighten the nuts, they need no retorquing, and are very reliable in a 4G63.
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Joined: Oct 2012
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From: Sydne, NSW
Hello, i am running an fb black on a 2.2. block, pushing 32lbs of boost, i have arp headstuds, roughly 600 on a dynojet, at what point to i o-ring the block, i blew a cosworth headgasket after about 10k miles, i am currently running a cometic but i havent put many miles on it
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Joined: Aug 2012
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From: Minnesota
Thanks for the great info... But instead of just assuming I was the one who had it built and putting in your comments, you should think of making a post that is actually helpful and worth reading...
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